Yes / It has been globally recognized as necessary to reduce greenhouse gas (GHG) emissions for mitigating the adverse effects of global warming on earth. Carbon dioxide (CO2) capture and storage (CCS) technologies can play a critical role to achieve these reductions. Current CCS technologies use several different approaches including adsorption, membrane separation, physical and chemical absorption to separate CO2from flue gases. This study aims to evaluate the performance and energy savings of CO2capture system based on chemical absorption by installing an intercooler in the system. Monoethanolamine (MEA) was used as the absorption solvent and Aspen HYSYS (ver. 9) was used to simulate the CO2capturing model. The positioning of the intercooler was studied in 10 different cases and compared with the base case 0 without intercooling. It was found that the installation of the intercooler improved the overall efficiency of CO2recovery in the designed system for all 1-10 cases. Intercooler case 9 was found to be the best case in providing the highest recovery of CO2(92.68%), together with MEA solvent savings of 2.51%. Furthermore, energy savings of 16 GJ/h was estimated from the absorber column alone, that would increase many folds for the entire CO2capture plant. The intercooling system, thus showed improved CO2recovery performance and potential of significant savings in MEA solvent loading and energy requirements, essential for the development of economical and optimized CO2capturing technology.

Mechanisms of reactions of the frustrated Lewis pairs (FLPs) with carbon dioxide (CO2) and hydrogen (H2) are studied by using quantum chemical modelling. FLPs are relatively novel chemical systems in which steric effects prevent a Lewis base (LB) from donating its electron pair to a Lewis acid (LA). From the main group of the periodic table, a variety of the electron pair donors and acceptors can create an FLP and the scope of the FLP chemistry is rapidly expanding at present. Representative intermolecular FLPs are phosphines and boranes with bulky electron-donating groups on phosphorus and bulky electron-withdrawing groups on boron – e.g., the tBu3P/B(C6F5)3 pair. The intramolecular FLPs feature linked LB and LA centers in one molecule. Investigations of the FLP reaction mechanisms were carried out using the transition state (TS) and the potential energy surface (PES) calculations plus the Born-Oppenheimer molecular dynamics (BOMD) as an efficient and robust implementation of general ab initio molecular dynamics scheme. In BOMD simulations, quantum and classical mechanics are combined. The electronic structure calculations are fully quantum via the density functional theory (DFT). Molecular motion at finite (non-zero) temperature is explicitly accounted for at non-quantized level via Newton’s equations. Due to recent advancements of computers and algorithms, one can treat fairly large macromolecular systems with BOMD and even include significant portion of the first solvation shell surrounding a large reacting complex in the molecular model. Main results are as follows. It is shown that dynamics is significant for understanding of FLP chemistry. The multiscale nature of motion – i.e., light molecules such as CO2 or H2 versus a pair of heavy LB and LA molecules – affects the evolution of interactions in the reacting complex. Motion which is perpendicular to the reaction coordinate was found to play a role in the transit of the activated complex through the TS-region. Regarding the heterolytic cleavage of H2 by tBu3P/B(C6F5)3 FLP simulated in gas phase and with explicit solvent, it was found that (i) the reaction path includes shallow quasi-minima “imbedded” in the TS-region, and (ii) tBu3P/B(C6F5)3 are almost stationary while proton- and hydride-like fragments of H2 move toward phosphorous and boron respectively. For binding of CO2 by tBu3P/B(C6F5)3 FLP, it was found that (i) the reacting complex can “wander” along the “potential energy wall” that temporarily blocks the path to the product, and (ii) the mechanism can combine the concerted and two-step reaction paths in solution. The discovered two-step binding of CO2 by tBu3P/B(C6F5)3 FLP involves solvent-stabilized phosphorus-carbon interactions (dative bonding). These and other presented results are corroborated and explained using TS and PES calculations. With computations of observable characteristics of reactions, it is pointed out how it could be possible to attain experimental proof of the results. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Accepted.</p><p> </p>

Este trabalho tem por objetivo avaliar a viabilidade técnica de processos de separação de gás carbônico em correntes de gases de combustão. Neste sentido, a separação por meio de membranas e por criogenia são avaliadas por meio de simulação de sistemas. As propostas envolvendo membranas avaliam arranjos de membranas em série, os quais são otimizados para condições de maior fluxo permeado e maior beneficio econômico. A corrente de alimentação é de 5 kmol/s e as respectivas frações molares de CO2 e N2 que compõem esta corrente são 0,15 e 0,85. Os resultados obtidos da otimização, para um arranjo de três membranas em série de polyimida de 9000 m² de área superficial, foram uma corrente de permeado de 443,1 mol/s de CO2 a 41,6%, correspondendo a aproximadamente 59% do CO2 da corrente de alimentação. Já com um arranjo de 6 membranas de 9000 m², onde a função objetivo é o maior lucro, foi selecionado o material kapton e a quantidade de CO2 separada é 161,12 mol/s, cuja concentração na mistura é de 79%, e a função objetivo tem um valor de 24.405,30 €/ano. Na outra parte do trabalho, propõe-se e avalia-se um ciclo para o aproveitamento da disponibilidade térmica na regasificação do gás natural líquido, para liquefação de CO2. Obtém-se como resultando em CO2 líquido com fração molar igual a 94%. Este processo consta de uma corrente proveniente da combustão completa de 1 mol/s de metano, contendo 1 mol/s de CO2 e 7,52 mol/s de N2. Esta corrente é comprimida e resfriada até atingir a pressão de 4000 kPa e 25 °C, posteriormente uma membrana enriquece a corrente de gases de combustão, que novamente é comprimida e resfriada até se obter a condensação e separação do CO2. Realiza-se o cálculo de equilíbrio líquido-vapor da mistura utilizando as equações de Peng-Robinson e a regra de mistura de Van der Waals no software VRTherm. A vazão molar do CO2 líquido obtida é de 0,3207 mol/s na concentração declarada. A intensidade energética do processo é de 1,135 kWh/kg de CO2 liquefeito. / The objective of this work is to evaluate the technical feasibility of carbon dioxide separation processes of flue gases streams. In this way, separation processes due membrane and cryogenics are evaluated by system simulation. The systems using membranes evaluates setup of those membranes in series, these setups are optimized for the largest permeate molar flow and the largest economic profit. The feed stream is a 5 kmol/s CO2 – N2 mixture, with molar fraction of 0.15 and 0.85 respectively. The result obtained from the optimization for a setup of three polyimide membranes of 9000 m² is a permeate stream of 443.1 mol/s with CO2 at 41.6%, corresponding to aproximadely 59% of the CO2 contained in the feed stream. When a setup of six 9000 m² membranes is analyzed using an objective function that results in the largest profit, kapton was selected as the material for the membranes. The quantity of CO2 captured is 161.12 mol/s, at 79% of concentration in the mixture, and the objective function has a value of 24,405.30 €/year. The second part of this work, proposes and evaluates a cycle that takes the thermal availability of the regasification of liquid natural gas in advantage for CO2 liquefaction. The product of the cycle is liquid CO2, with a molar fraction of 0.94. The process is fed with a stream that comes from the stoichiometric combustion of 1 mol/s of methane, that stream is composed by 1 mol/s of CO2 and 7.52 mol/s of N2. The stream is then compressed up to the pressure of 4000 kPa and cooled down to 25 °C. After that a membrane concentrates the CO2 in one stream, which is again compressed and cooled down until the condensation of CO2 is achieved. Calculations of liquid – vapor are performed with the Peng- Robinson’s equations and the Van der Waals mixture rule using the software VRTherm. The molar flow rate of liquid CO2 obtained is of 0.3207 mol/s in the concentration mentioned before. The energy intensity of the process is of 1.135 kWh/kg of liquid CO2.

Le procédé de captage du CO2 en post-combustion par absorption chimique est aujourd'hui la technologie la plus mature en vue d'une réduction des émissions de CO2 issues de procédés industriels. Les deux principales limitations de la technologie sont la pénalité énergétique engendrée par le procédé, et la formation de produits de dégradation potentiellement toxiques pour l'Homme et l'environnement. Dans le cadre de ce projet de thèse, trois solvants innovants ont été présélectionnés pour leurs bonnes propriétés thermodynamiques de captage : les mélanges 1-méthylpipérazine / pipérazine (1MPZ /PZ), diméthylaminoéthanol / pipérazine (DMEA/PZ) et méthyldiéthanolamine/monoéthanolamine (MDEA/MEA). Ces trois solvants ont été étudiés en termes de stabilité chimique dans des conditions représentatives des conditions industrielles du captage de CO2 en post-combustion sur un dispositif expérimental construit par EDF R&D Chatou. Des méthodes analytiques complémentaires impliquant les chromatographies liquide et gazeuse ont été développées dans l'objectif de suivre les teneurs en amines constituantes du solvant au cours du temps, et d'identifier et quantifier les potentiels produits de dégradation formés aussi bien dans la phase liquide du solvant que dans les fumées traitées émises. Au vu des résultats obtenus au cours de ce projet, le solvant MDEA/MEA semble offrir le meilleur compromis en termes de stabilité chimique et de besoins énergétiques requis pour le procédé. Ce solvant présente des taux de dégradation inférieurs aux mélanges 1MPZ/PZ et DMEA/PZ, et permettrait une réduction de l'énergie au rebouilleur de l'ordre de 10 % par rapport à la MEA 30 %, solvant modèle au procédé. / Post-combustion CO2 capture using amine solvents is nowadays the most promising technology to limit the CO2 emissions from already existing power plants. The two main limitations of the process are the high energy penalty and the irreversible degradation of amines involving the formation of degradation products potentially toxic for human and the environment. Within the scope of this project, three innovative solvents were selected for their good thermodynamic properties for CO2 capture: the blends 1-methylpiperazine / piperazine (1MPZ/PZ), dimethylaminoethanol / piperazine (DMEA/PZ) and methyldiethanolamine/monoethanolamine (MDEA/MEA). The three blends were degraded in conditions representative of industrial conditions for post-combustion CO2 capture on a lab scale pilot plant constructed by EDF R&D. Complementary analytical methods involving gas and liquid chromatography were developed in order to monitor the stability of the constituent amines, and to identify and quantify potential degradation products formed. These methods permitted the characterization of both the liquid phase of the solvent and the gaseous phase corresponding to the treated flue gas. Results obtained during this project showed that the blend MDEA/MEA would offer the best compromise in terms of chemical stability and energy needed for the process. This solvent presents degradation rates lower than the blends 1MPZ/PZ and DMEA/PZ and would enable a reduction of the reboiler heat duty in the range of 10% when compared to MEA 30% the benchmark solvent of the process.

The risk for climate change is a growing concern for theglobal society. According to what is known as the Kyoto Protocol,developed countries have committed themselves to reduce theirgreenhouse gas (GHG) emissions. The purpose of this thesis hasbeen to analyse opportunities for CO2 reductions in Swedish pulpand paper mills. The pulp and paper industry accounts forsignificant shares of the Swedish utilisationof both electricityand, in particular, biomass fuels. In this thesis, it has been agoal to focus not only on the technical potential of alternativesfor CO2 reductions in the energy systems of pulp and paper mills,but also on analysing the costeffectiveness of the studiedmeasures. Moreover, the analysis has covered questions concerningthe capacity and willingness among the actors involved with thepulp and paper mills’energy systems to realise CO2reduction potentials. A broad techno-economical evaluation of available technologiesfor increased power production as well as more efficient energyutilisation is carried out. Furthermore, a more indepth analysisof pulp mill-based biomass energy with CO2 removal and permanentsequestration (BECS) is presented. An evaluation is made of thepotential for pulp and paper production with a negative CO2balance through the implementation of BECS. In recent yearsoutside suppliers, mainly energy service companies (ESCOs), havebegun to operate energy facilities in some Swedish pulp and papermills. Based on interviews with managers from pulp and papercompanies and ESCOs, the main driving forces behind theincreasing co-operation as well as the opportunities and riskswith energy related co-operation are presented. Furthermore, the technical possibility of carbon-negativitythrough the implementation of BECS is discussed in relation tocarbon management on both corporate and global levels. The extentto which CO2-reducing measures in pulp and paper mills arerealised will have an impact on Sweden’s capacity to reachCO2 reduction targets. Whether or not technologies for CO2capture and sequestration are developed and implemented inSwedish pulp mills has a very large impact on the size ofSweden’s long-term CO2 reduction potential. Moreover, thedevelopment of business and competence focus in pulp and papercompanies and ESCOs suggests that cooperation will become ofincreasing importance for future sustainable industrial energymanagement. <b>Keywords:</b>CO2 reduction, pulp and paper industry, energysystem, biomass, CO2 capture and sequestration, black liquor,gasification, power production, outsourcing, sustainable energymanagement

Oxy-fuel combustion technology, which is based on burning coal in a mixture of oxygen and recycled flue gas (RFG), is suggested as one of new promising technologies for capturing CO2 from power plants. In this thesis study, the pyrolysis and combustion behaviour of various fuels including imported coal, petroleum coke, two different types of indigenous lignites, olive residue and their blends with different proportions in air and oxy-fuel conditions were investigated by using non-isothermal thermogravimetric method (TGA) coupled with Fourier-transform infrared (FTIR) spectrometer. Pyrolysis tests were carried out in nitrogen and carbon dioxide environments, which are the main diluting gases of air and oxy-fuel environment, respectively. Pyrolysis results reveal that weight loss profiles are similar up to high temperature zone in both pyrolysis environments, indicating that CO2 behaves as an inert gas in this temperature range. However, further weight loss takes place in CO2 atmosphere v after 700oC due to CO2-char gasification reaction which is observed in pyrolysis of all fuel samples. Combustion experiments were carried out in four different atmospheres / air, oxygen-enriched air environment (30 % O2 &ndash / 70 % N2), oxy-fuel environment (21 % O2 &ndash / 79 % CO2) and oxygen-enriched oxy-fuel environment (30 % O2 &ndash / 70 % CO2). Combustion experiments show that replacing nitrogen in the gas mixture by the same concentration of CO2 does not affect the combustion process significantly but leads to slight delay (lower weight loss rate and higher burnout temperature) in combustion. Overall comparison of weight loss profiles shows that higher oxygen content in the combustion environment is the dominant factor affecting the combustion rather than the diluting gas. As O2 concentration increases profiles shift through lower temperature zone, peak and burnout temperatures decrease, weight loss rate increases and complete combustion is achieved at lower temperatures and shorter times. Pyrolysis and combustion behaviour of three different fuel blends were also investigated. Results reveal synergistic interactions in combustion tests of all blends in all combustion environments. During pyrolysis and combustion tests gaseous products CO2, CO, H2O, CH4, SO2 and COS were identified in flue gas and analyzed by using FTIR. Results indicate that higher CO and COS formation take place during pyrolysis tests due to gasification reaction in CO2 atmosphere at high temperature zone. Gaseous species evolution trends in combustion tests are found specific for each fuel. However, evolution trends slightly shift to lower temperatures in oxygen-enriched conditions.

<p>The risk for climate change is a growing concern for theglobal society. According to what is known as the Kyoto Protocol,developed countries have committed themselves to reduce theirgreenhouse gas (GHG) emissions. The purpose of this thesis hasbeen to analyse opportunities for CO2 reductions in Swedish pulpand paper mills. The pulp and paper industry accounts forsignificant shares of the Swedish utilisationof both electricityand, in particular, biomass fuels. In this thesis, it has been agoal to focus not only on the technical potential of alternativesfor CO2 reductions in the energy systems of pulp and paper mills,but also on analysing the costeffectiveness of the studiedmeasures. Moreover, the analysis has covered questions concerningthe capacity and willingness among the actors involved with thepulp and paper mills’energy systems to realise CO2reduction potentials.</p><p>A broad techno-economical evaluation of available technologiesfor increased power production as well as more efficient energyutilisation is carried out. Furthermore, a more indepth analysisof pulp mill-based biomass energy with CO2 removal and permanentsequestration (BECS) is presented. An evaluation is made of thepotential for pulp and paper production with a negative CO2balance through the implementation of BECS. In recent yearsoutside suppliers, mainly energy service companies (ESCOs), havebegun to operate energy facilities in some Swedish pulp and papermills. Based on interviews with managers from pulp and papercompanies and ESCOs, the main driving forces behind theincreasing co-operation as well as the opportunities and riskswith energy related co-operation are presented.</p><p>Furthermore, the technical possibility of carbon-negativitythrough the implementation of BECS is discussed in relation tocarbon management on both corporate and global levels. The extentto which CO2-reducing measures in pulp and paper mills arerealised will have an impact on Sweden’s capacity to reachCO2 reduction targets. Whether or not technologies for CO2capture and sequestration are developed and implemented inSwedish pulp mills has a very large impact on the size ofSweden’s long-term CO2 reduction potential. Moreover, thedevelopment of business and competence focus in pulp and papercompanies and ESCOs suggests that cooperation will become ofincreasing importance for future sustainable industrial energymanagement.</p><p><b>Keywords:</b>CO2 reduction, pulp and paper industry, energysystem, biomass, CO2 capture and sequestration, black liquor,gasification, power production, outsourcing, sustainable energymanagement</p>

<p>Nanotechnology is a relatively new research topic that attracts increasing interest from scientists and engineers all over the world, due to its novel applications. The use of nanomaterials has extended to a broad range of applications, for example chemical synthesis, microporous media synthesis and catalytic combustion, contributing to achievement of improved or promising results. Microemulsion (ME) is considered a powerful tool for synthesis of nanomaterials, due to its unique properties. This thesis concentrates on the use of the ME as a catalyst synthesis route for obtaining metal nanoparticles for two challenging concepts: Hydrogen production by a membrane reactor and selective catalytic oxidation (SCO) of ammonia in gasified biomass.</p><p>Particularly for the scope of the fist concept presented in this thesis, palladium nanoparticles were synthesised from ME in order to be deposited on zeolite composite membranes to improve the H₂ / CO₂ separation (hydrogen production) ability. The membranes impregnated with Pd nanoparticles were then tested in a metal reactor for the permeance and selectivity towards H₂ and CO₂. Regarding the second concept, cerium-lanthanum oxide nanoparticles were prepared by conventional methods and from ME in order to be tested for their activity towards SCO of ammonia in gasified biomass.</p><p>The environmental importance of these two applications under investigation is great, since both are involved in processes contributing to the minimisation of the harmful exhaust gases released to the atmosphere from numerous industrial applications, such as the oil industry and heat-and-power production (for example combustion of natural gas or biomass in a gas turbine cycle). Regarding these applications, separation and capture of CO₂ from exhaust gases and oxidation of the fuel-bound ammonia in gasified biomass directly to nitrogen, minimising at the same time NO_xformation, are rated as very important technologies. The results obtained from this work and presented analytically in this thesis are considered successful and at the same time promising, since further research on the ME method can even lead to improvement of the current achievements.</p><p>The first part (Chapter 2) of the thesis gives a general background on the ME method and the applications in the two concepts under investigation. Additionally, it describes how the nanoparticles corresponding to the concepts were synthesised.</p><p>The second part (Chapter 3) of the thesis describes the different Pd-nanoparticle impregnation methods on the zeolite composite membranes and the results obtained form the permeation tests. In parallel with impregnation methods, various aspects that affect the Pd impregnation efficiency and the membrane performance such as duration, temperature and calcination conditions are discussed thoroughly.</p><p>The third and final part of the thesis (Chapter 4) concerns the preparation of the cerium-lanthanum oxide catalysts and the activity tests (under simulated gasified biomass fuel conditions) carried out in order to monitor the activity of these catalysts towards the SCO of ammonia. Additionally, a comparison of the activity between identical catalysts prepared by conventional methods and the ME method is discussed.</p>

Carbon capture and storage (CCS) and a point of electricity generation is a promising option for mitigating greenhouse gas emissions. One issue with respect to CCS is the design of carbon dioxide transport, storage and injection system. This dissertation develops a model, OptimaCCS, that combines economic and spatial optimization for the integration of CCS transport, storage and injection infrastructure to minimize costs. The model solves for the lowest-cost set of pipeline routes and storage/injection sites that connect CO2 sources to the storage. It factors in pipeline costs, site-specific storage costs, and pipeline routes considerations involving existing right of ways and land use. It also considers cost reductions resulting from networking the pipelines segment from the plants into trunk lines that lead to the storage sites. OptimaCCS is demonstrated for a system involving carbon capture at 14 Texas coal-fired power plants and three potential deep-saline aquifer sequestration sites. In turn OptimaCCS generates 1) a cost-effective CCS pipeline network for transporting CO2 from all the power plants to the possible storage sites, and 2) an estimate of the costs associated with the CO2 transport and storage. It is used to examine variations in the configuration of the pipeline network depending on differences in storage site-specific injection costs. These results highlight how various levels of cooperation by CO2 emitters and difference in injection costs among possible storage sites can affect the most cost-effective arrangement for deploying CCS infrastructure. This study also analyzes CCS deployment under the features in a piece of legislation the draft of American Power Act (APA) - that was proposed in 2010 which contained a goal of CCS capacity for emissions from 72 Gigawatt (GW) by 2034. A model was developed that simulates CCS deployment while considering different combinations of carbon price trajectories, technology progress, and assumed auction prices. The model shows that the deployment rate of CCS technology under APA is affected by the available bonus allowances, carbon price trajectory, CCS incentive, technological adaptation, and auction process. Furthermore it demonstrates that the 72GW objective can only be achieved in a rapid deployment scenario with quick learning-by-doing and high carbon price starting at 25 dollars in 2013 with a 5 percent annual increase. Furthermore under the slow and moderate deployment scenarios CCS capacity falls short of achieving the 72 GW objective.

La synthèse contrôlée de nanoparticules constitue toujours un enjeu majeur en science des matériaux (pour des applications telles que la catalyse par exemple) et la voie «fluides supercritiques» permet de répondre en partie à ce challenge. Dans ce contexte, ce travail de thèse a été consacré à l’élaboration de nanostructures d’oxyde de cérium aux caractéristiques contrôlées (tailles, morphologies, propriétés de surface,…) par synthèse solvothermale supercritique. A partir de l’étude de l’influence des paramètres opératoires du procédé sur les caractéristiques physico-chimiques des nanomatériaux obtenus, des mécanismes de formation et de fonctionnalisation de surface ont été proposés. D’un point de vue applicatif, ces poudres ont été caractérisées qualitativement et quantitativement vis-à-vis de la capture réversible du CO2. / The controlled synthesis of nanoparticles remains of key importance in materials science (for applications such as catalysis for instance) and “supercritical fluids” processes allow partially addressing this challenge. In this context, this PhD work has been dedicated to the synthesis of cerium oxide nanostructures with controlled characteristics (size, morphology, surface property,…) by supercritical solvothermal approaches. Through the study of the influence of process operating parameters on physicochemical characteristics of the synthesized materials, formation and surface modification mechanisms have been proposed. From an applicative point of view, powders have been submitted to qualitative and quantitative characterization towards CO2 capture.